I am developing a Python tool to simulate energy efficiency in smart homes. I need to calculate the heat transfer coefficient (U-value) when adding a window film layer. Given the Visible Light Transmittance (VLT) and Total Solar Energy Rejected (TSER) as inputs, what is the most efficient way to model the conductive vs. radiative heat gain in a 2D grid simulation? Are there existing libraries for handling spectral data of thin-film materials?